This invention relates to irrigation systems, and in particular to a drip irrigation system having grouped distribution lines and a sequencing water valve arrangement.
In agriculture, drip or trickle irrigation is a well known method of distributing water directly to the base or roots of plants or trees at an extremely low rate, whereby there is substantially no surface run off of the water, and evaporation of the irrigation water is minimized. To effect the slow application of irrigation water, the water distribution lines include emitters having extremely small orifices therein. Because the application rate of the water is very slow in drip irrigation, water is distributed to the soil for extended periods of time, occasionally nearly continuously, during the day to provide sufficient moisture for the crops.
Heretofore, drip irrigation systems have experienced a serious problem regarding the clogging of the small orifices in the emitters by foreign material suspended in the irrigation water. Typically, the irrigation water is supplied from a well, a reservoir, or the like, and contains a substantial amount of foreign material, such as sediment or debris in the nature of silt, clay, microorganisms, sand, etc. These foreign materials must be filtered from the irrigation water and/or the water treated with expensive chemicals to avoid clogging the emitter orifices, and to alleviate consequent maintainence and repair problems. This is particularly true in subterranean drip irrigation systems, wherein the emitters are buried beneath the surface of the soil. Subterranean drip irrigation systems are however, extremely efficient, and are particularly useful in arid regions. In present drip irrigation systems, if the foreign materials are not removed, and the emitters become clogged, repair to the system is not only time-consuming and expensive, but may result in complete crop failure or tree loss if the system is not brought to an operative condition within a relatively short period of time.